Device for reading meniscuses



Feb 7 195 F. DRESSER zgwfifmc? DEVICE FOR READING MENISCUSES Filed June 27, 1947 IN VEN TOR.

Patented Feb. 7, 1950 UNITED STATES ATENT OFFICE i Claims.

The present invention relates to a device for reading a meniscus. More especially it has to do with a device which can be applied readily to a burette or similar tubular container and moved therealong until the exact location of the meniscus of the liquid in the container is accurately determined.

Present methods of meniscus reading render accurate results diflicult if not impossible to attain because they depend solely on the human eye for proper alignment with the meniscus, and on light rays emanating from various sources. Readings thus taken are not accurate enough for all purposes, and to this end I have provided an improved device so constructed as to assure accurate readings at all times.

The principal object of my invention is to provide a device adapted to slide along a burette tube and having spaced horizontally etched lines which insure the eye being in exact alignment with the meniscus of the liquid in the tube.

Another object is to provide a source of illumination at the level of and behind the meniscus with a diffusing lens and ground glass plate to give an even field of light against which the meniscus is sharply outlined.

With these and other objects and advantageous features in mind the invention is more fully disclosed in the accompanying description, drawings, and appended claims.

In the drawings:

Fig. 1 is a perspective view of the improved device mounted on a burette tube; and

Fig. 2 is a side elevation of the same showing the forward portion thereof in medial section.

Referring now to the drawings, the improved device it] is mounted on a burette tube l2 having graduations l4 thereon which indicate measured distances from some reference point or the quantity of liquid within the tube. The device comprises a pair of plates 55, preferably made of fiber, suitably secured together in vertically spaced relation by angle plates l8 and suitable bolts 23. The front edges of these plates it have notches or recessed spaces 22, the rear portions of which are V-shaped so that when the tube i2 is within the notches it will be centered by engagement with the sides of the V.

Rearward of the plates 18 is mounted a tubular handle 24 having thereon a resilient contact lever 26 electrically connected with a wire 23 leading from some source of electric current. Another wire 3!! from the same source is connected with a band 32 insulatedly mounted on the handle 24 in position to be engaged by a contact point 2611 on the lever 26. The current supplied to the wires 28 and 3D is of such low voltage as to be unnoticed by a hand gripping the handle and moving the lever into circuit making contact.

When the circuit is closed, a small lamp 34 projecting forwardly from the handle 24 is lighted. Just ahead of this lamp is a diffusing lens 36 and ahead of this lens is a ground glass plate 38 which is uniformly illuminated by the diffused light from the lamp 34. The plate 38 is close by the tube 12 and provides a well-lighted field behind the meniscus 40 of the liquid in the tube. v

In front of the tube is a vertical plate 42 having a rectangularly shaped central opening 42a. This plate 42 is hinged as at 44 to one of the angle plates l8 and from the other angle plate l8 a latch 46 extends to engage the plate 42 when it is swung toward the glass tube [2. On the rear surface of the plate 42 is a glass plate 48 overlying the rectangular opening 42a. When the plate 4'2 is engaged by the latch l8, there is a slight space between the glass plate and the burette tube thereby providing for easy and free movement of the device along the burette tube.

Secured to the plate 42 around the rectangular opening 420. is a forwardly extending rectangularly shaped tube 52. This carries at its front end a glass plate 54 suitably secured to the tube. Both this glass plate 54 and the glass plate 48 are etched with fine horizontal lines 56 and 58 respectively. These lines are in alignment in a plane perpendicular to the vertical axis of the burette tube l2.

In using the device, the observer sights through the rectangular tube 52 as he moves the device along the burette tube l2 by means of the handle 24. He keeps the contact point 2611 closed against the contact band 32 thus keeping the lamp 34 lighted. When the two etched lines 56 and 58 are brought into absolute alignment with the surface of the meniscus 40 the observer then reads the graduation l4 on the tube [2.

By having what amounts to three lines of reference (the two lines 56 and 58, and the surface of the meniscus which, because the diffused light behind, it appears as another line) all of which must be viewed in perfect alignment, the observer is thereby forced to make an accurate observation of the meniscus.

I claim:

1. A device for reading a meniscus comprising a pair of plates in vertical spaced relation each having a V-shaped notch adapted to be engaged by a tube containing the liquid whose meniscus is to be read; a lamp supported by means attached to said plates; a diffusing lens between said lamp and a tube engaged in said notches and a ground glass plate between said lens and the tube; a tubular element supported by said plates on the side opposite the tube from that side on which the lamp is located; horizontally displaced glass plates carried by said tubular element each having a horizontal reference line thereon in a plane perpendicular to the axis of the tube; the said device being slidable along the tube until the said two lines and the surface of the meniscus of the liquid are brought into alignment.

2. A device for reading a meniscus comprising means for providing a source of light on one side of a tube containing the liquid whose meniscus is to be read; means between said light source and the tube for diffusing the light and providing a uniformly illuminated field on said side of the tube; means on the opposite side of the tube providing two horizontally disposed reference lines in spaced relation to one another and to the tube and lying in a plane perpendicular to the axis of said tube; the said device being movable along the tube to bring the said reference lines and the surface of the meniscus of the liquid into alignment.

3. A device for reading a meniscus comprising means providing horizontally disposed V-shaped notches in vertically spaced relation for engaging the wall of a tube containing'a liquid whose meniscus is to be read, said spaced engagement insuring that the longitudinal axis of the device shall be maintained perpendicular to the axis of said tube; means on the same side of said tube as are said notches providing a uniformly illuminated field on one side of the meniscus; and means on the other side of said meniscus comprising horizontal reference lines disposed in spaced relation from the tube at right angles to the said longitudinal axis of the device; the said device being slidable along said tube to bring the said reference lines and the surface of the meniscus into alignment.

4. A device for reading a meniscus comprising spaced apart means for slidably engaging a tube containing a liquid whose meniscus is to be read, the said engaging means maintaining the longitudinal axis of the device perpendicular to the vertical axis of the tube while the device is slipped along the tube; and means extending outwardly from the tube on one side thereof having two horizontal reference lines in spaced relation to one another and to the tube within a plane perpendicular to the axis of the tube; the said device being slidable along the tube to bring the said reference lines and the surface of the meniscus into alignment.

FRANK G. DRESSER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,736,136 Schuhmann Nov. 19, 1929 2,111,221 Mitchell Mar. 15, 1938 

